Vietnamese coffee exporters have delayed loading of around 40,000 tons, or nearly 670,000 bags, due to thin domestic stocks and a jump in local market prices beyond export levels, traders said on Tuesday.

The delayed volume in Vietnam, plus up to 12,000 tons in shipment cancellations in Indonesia, may pile pressure on the buyers involved but would not reverse a price fall in London following favorable crop weather in top producer Brazil.

Vietnam and Indonesia are the world's largest producers of robusta coffee, altogether accounting for 20 percent of global output in the current 2010/2011 crop, based on the International Coffee Organization's (ICO) May report.

Around two thirds of the volume were delayed by two exporters, including a major company in the Central Highlands coffee belt, while several smaller firms made up the remaining quantity, traders in Ho Chi Minh City said.

The export volume at risk is equivalent to 30 percent of the 2.2 million-bag average monthly volume shipped by Vietnam, the world's largest producer of robusta beans.

"Some of these 40,000 tons could face washouts, but the final volume of defaults is not clear yet as it depends on companies talking with each other," a trader said.

The volume is part of the 100,00 tons due for loading since May, based on an estimate by a senior Vietnamese industry official last month.

Vietnam, which accounts for 14 percent of global output, may have 2.5 million bags left from the latest harvest of 22 million bags as estimated by traders, Reuters calculations show.

Coffee prices in Vietnam have risen by nearly a third so far this year from the end of 2010, based on Reuters calculations, making it difficult for several exporters to secure beans from domestic markets for delivery, traders said.

Prices at premiums

Last month Vietnamese robusta beans were traded at premiums to London prices for the first time since mid-2010, as stocks tightened after strong exports in the first months of this year.

Robusta beans stood at VND48.7-48.9 million dong ($2,370-$2,380) per ton in Daklak, the country's top growing province, on Tuesday, up from 37.1 million dong on Dec. 31, 2010.

But prices eased around 4 percent from 50.6-51 million dong a ton last Tuesday after London robusta futures fell following a sharp setback in ICE arabica coffee and overall weakness in commodity markets.

"Buying demand is thin, and with the price drop exporters have not made any quotations today," another trader said.

The first trader said buyers of Vietnamese coffee could now switch to buying directly in Europe, instead of taking more expensive beans from Vietnam.

Indicative offers of Vietnamese robusta showed a premium of $100 per ton to London's September contract , unchanged from last Tuesday, but no deals were seen, traders said.

It meant that robusta grade 2, 5 percent black and broken was priced at $2,454 a ton, free-on-board, from $2,470 last Tuesday.

"Buyers now could only be in Asia and are likely those who have to fill in the volume delayed so far by Vietnamese exporters," the first trader said.